Siegel der Universität

Universität zu Köln
line
Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut

Infrared instrumentation for Large Interferometric Arrays (position 2)

The institute is already strongly involved in several international projects e.g. for VLTI, LBT, SOFIA, Herschel, JWST, APEX, ALMA. In the context of the institute involvement in long-baseline interferometry, the 1st Physics Institute coordinates the BMBF-funded instrumentation project ALSI (Advanced Laser- writing for Stellar Interferometry) in collaboration with the University of Jena and the Max-Planck Institute for Astronomy in Heidelberg, which are among the major institutions in the field of astronomical instrumentation. The ALSI project is aiming at developing new photonic-based solutions fabricated by ultrafast laser writing techniques, which will become the future key components for interferometric multi-aperture beam combination and fringe- tracking.

Within this project, the student will develop the theory for fringe tracking at the sensitivity limit, with emphasize on group delay tracking, multi-wavelength fringe prediction, Bayesian fringe position estimation, active dispersion control.

Details are found here

Infrared instrumentation for Large Interferometric Arrays

The institute is already strongly involved in several international projects e.g. for VLTI, LBT, SOFIA, Herschel, JWST, APEX, ALMA. In the context of the institute involvement in long-baseline interferometry, the 1st Physics Institute coordinates the BMBF-funded instrumentation project ALSI (Advanced Laser- writing for Stellar Interferometry) in collaboration with the University of Jena and the Max-Planck Institute for Astronomy in Heidelberg, which are among the major institutions in the field of astronomical instrumentation. The ALSI project is aiming at developing new photonic-based solutions fabricated by ultrafast laser writing techniques, which will become the future key components for interferometric multi-aperture beam combination and fringe- tracking. 

Within this project, the student will focus on building the multi-aperture interferometric lab test bench in the K and L bands. Under the supervision of the group’s staff, the student will take responsibility of the interferometric lab characterization phase to validate the technology and provide feedback to our technological partner in Jena, with whom he/she will be in regular contact and report to through frequent visits. The goal of the PhD project is to demonstrate that laser-written integrated-optics hardware is technically suitable for interferometric combination in the K and L bands. 

Details are found here

Observational astrophysics using interferometry and adaptive optics

The position is opened for working in observational astrophysics at high angular resolution in the field of star formation, with an emphasis on using stellar interferometry with the VLTI facility in Chile. The PhD candidate will work under the co-supervision of Prof. Lucas Labadie (University of Cologne) and Prof. Gerd Weigelt (Max-Planck Institute for Radio Astronomy, Bonn).

Applicants should hold the equivalent of a MSc or Diploma degree in physics or astronomy. She/He should have ideally gained first experience with astronomical research, and have a background in the field of star formation and/or in stellar interferometry or adaptive optics. Experience with a standard programming language (C/C++/IDL/Matlab) is an asset.

Details are found here.

High Mass Star Formation/Astrochemistry

There currently is no funding for PhD positions, if you come with your own funding, feel free to contact me and a suitable topic in my research interests can be found.

The origin of [CII] emission on large scales

Betreuer: Volker Ossenkopf und Jürgen Stutzki

The [CII] line at 158 micron is next to the [OI] 63 micron line the most important cooling line of the interstellar medium in the Milky Way (Fixsen et al.) and in external galaxies (Stacey et al. 1991, Malhotra et al.). The new observatories SOFIA and Herschel will allow to map the [CII] line at unprecedented spatial resolutions and, for (almost) the first time, allow to resolve its velocity structure.

In prepartion of these studies, at least two problems need to be addressed:

  1. [CII] emission from the different phases of the ISM
    [CII] is emitted not only from surfaces of dense molecular clouds, but also from the cold, neutral HI clouds and the ionized components of the interstellar medium. While the average densities and temperatures thus vary strongly between the various phases of the ISM, the main common gas heating mechanism may be the photo-electric effect on dust grains. Thus, models of photon dominated regions like CLOUDY (or in fact KOSMA-tau) may be apropriate to model the [CII] emission from all phases.
    The [NII] lines at 205 and 122 micron stem only from the ionized components. Taking into account the N/C abundances and excitation conditions, observations of the [NII] have been used to estimate the relative importance of the dense and diffuse ionized phases and the contribution of these phases to the total observed [CII] emission (Carral et al. 1994).
    Cold, neutral HI clouds are expected to contribute significantly to the total [CII] cooling. However, the relative contribution to the total observed emission [CII] as function of galacto-centric distances or latitudes is yet unclear.
  2. [CII] emission line profiles
    An open issue is the interpretation of [CII] line shapes. It may be possible to use the line shapes to deconvolve the contribution of the different phases, but it remains to be shown that this is possible. Model studies of Hennebelle & Perault (2000) may show the way. Complementary HI data is needed here.

Model predictions shall be compared with already available observational data of the two nearby galaxies M83 or M51. The data comprises ISO/LWS FIR data as well as others. It is planned to obtain complete maps with NANTEN2 in the lines of atomic carbon and mid-J transitions of carbon monoxyde. The thesis aim is to prepare as best as possible for the oncoming [CII] observations with GREAT/SOFIA and HIFI/Herschel. First data is expected for fall 2006.